diff --git a/src/nomad_simulations/schema_packages/utils/utils.py b/src/nomad_simulations/schema_packages/utils/utils.py
index cbb0ce98..6c1ec42b 100644
--- a/src/nomad_simulations/schema_packages/utils/utils.py
+++ b/src/nomad_simulations/schema_packages/utils/utils.py
@@ -18,19 +18,22 @@
 #
 
 from math import factorial
-from typing import List, Optional
+from typing import TYPE_CHECKING
 
 import numpy as np
-from nomad.datamodel.data import ArchiveSection
-from structlog.stdlib import BoundLogger
+
+if TYPE_CHECKING:
+    from typing import List, Optional
+    from nomad.datamodel.data import ArchiveSection
+    from structlog.stdlib import BoundLogger
 
 
 def get_sibling_section(
-    section: ArchiveSection,
+    section: 'ArchiveSection',
     sibling_section_name: str,
-    logger: BoundLogger,
+    logger: 'BoundLogger',
     index_sibling: int = 0,
-) -> Optional[ArchiveSection]:
+) -> 'Optional[ArchiveSection]':
     """
     Gets the sibling section of a section by performing a seesaw move by going to the parent
     of the section and then going down to the sibling section. This is used, e.g., to get
@@ -112,7 +115,7 @@ def degeneracy(self):
         )
 
 
-def is_not_representative(model_system, logger: BoundLogger):
+def is_not_representative(model_system, logger: 'BoundLogger'):
     """
     Checks if the given `ModelSystem` is not representative and logs a warning.
 
@@ -133,8 +136,8 @@ def is_not_representative(model_system, logger: BoundLogger):
 
 # cannot define typing with `Variables` due to circular import issue
 def get_variables(
-    variables: Optional[List[ArchiveSection]], variable_cls: ArchiveSection
-) -> List[ArchiveSection]:
+    variables: 'Optional[List[ArchiveSection]]', variable_cls: 'ArchiveSection'
+) -> 'List[ArchiveSection]':
     """
     Get the list of variables which are of type `variable_cls` and appear under `variables`.
 
@@ -155,7 +158,7 @@ def get_variables(
 
 
 # TODO remove function in nomad.atomutils
-def get_composition(children_names: List[str]) -> str:
+def get_composition(children_names: 'List[str]') -> str:
     """
     Generates a generalized "chemical formula" based on the provided list `children_names`,
     with the format X(m)Y(n) for children_names X and Y of quantities m and n, respectively.